1. Field of the Invention
The present invention relates to a control device which actuates a camera at predetermined times e.g. at desired hours, at desired intervals, or in a desired period, and which, in conjunction with the actuation of the camera, makes an electronic flash device ready for effecting flash firings for flash photographing in cooperation with the camera, thereby enabling periodic flash photographing such as effected for recording a plant's growth.
2. Description of the Prior Art
It is extremely important to restrict the current consumption as much as possible in making flash photographing periodically. Especially in the case when small dry cells or batteries such as alkaline or alkaline-manganese cells of the UM-3 type, are used for the power source of the electronic flash device, the batteries will be consumed in half a day at the longest if the voltage booster or DC-DC converter of the device is operated continuously, whereby it is impossible to make periodic flash photographing for as long a period such as several hours or one day. To cope with such inconvenience, a device proposed in a Japanese laid-open patent publication No. Sho 53-116148 is adapted to energize an electronic flash device for given periods before, on and after the times when the camera is to be actuated, and make the electronic flash device complete its preparation for flash firing, i.e. complete the charging of the main capacitor thereof before the time of the camera actuation. However, the proposed device is arranged so that a relay provided in the electronic flash device has its terminal connected in the power supply path to the booster circuit to energize and de-energize the latter through the terminals. The relay is energized by the power source of the electronic flash device and requires a large current of as much as several tens of milliamperes although the period of the energization of the relay is controlled by a control signal from a release control device. The large current is an unnecessary current consumption for the intrinsic operation of the electronic flash device. Additionally, to assemble such a relay within the electronic flash device makes the device cumbersome and is unfavourable considering the compactness of the device. Further, if the relay is to be replaced by a semiconductor element or circuit, a power transistor or transistors for high output power and having a large size must be used therein because a large current of as much as 10 amperes flows momentarily through the power supply path to the booster circuit, whereby even the adoption of such a semiconductor can not contribute to the compactness of the device.
In the aforementioned prior art device, the energization of the relay for the booster circuit is controlled through the terminal of another relay provided in the release control device. Accordingly, the release control device also requires an extra large current of as much as 10 milliamperes and is large in size.